This invention relates to a working cast which can be easily attached to and detached from an articulator, a cover for a working cast which also serves as a mold, and an articulator to which the working cast can be mounted.
To manufacture a crown restoration, a working cast is manufactured first. Then a master model and an antagonist model are mounted on an articulator to adjust the occlusion between the master model and the antagonist model.
As shown schematically in FIG. 20, such an articulator comprises a base 1 having a column 1a, and a support arm 3 pivotally mounted to the top of the column 1a by a pin 2. To mount a working cast, as shown in FIG. 21, plaster paste S1 is heaped on the base 1, and plaster paste S2 is also heaped on the top of a master model M1 whose bite with respect to an antagonist model M2 has been fixed by wax beforehand, and further a small amount of plaster paste S3 is optionally applied to the bottom of the support arm 3. Then, the models M1 and M2 are placed together on the paste S1, the support arm 3 is pivoted onto the master model M1, and positions of the models M1, M2 are adjusted in this state. Any excess plaster paste protruding from the outer periphery is removed by fingers or a knife.
It is thus extremely troublesome to mount a working cast on an articulator. It is also very time-consuming and low in efficiency to remove the model after the plaster has hardened. It is also necessary to remove plaster stuck on the bottom of the model.
An environment where crown restorations are manufactured is usually scattered with dust including plaster powder, metallic and ceramic powder and wax chips and thus extremely messy. Such dust tends to adhere to the models, thus necessitating cleaning of the models.
An object of this invention is to simplify the attaching and detaching of a working cast to and from an articulator, thereby markedly improving work efficiency.
Another object of this invention is to keep working casts as dust-free as possible.